In recent years, there has been an upward trend in the use of cannabis for both medicinal and recreational purposes. As public perceptions continue to evolve and a growing number of jurisdictions make cannabis products more freely available, figures show that people from all walks of life are increasingly embracing (or turning to) cannabis – including pregnant people.
This may be surprising, given the generally accepted view that using cannabis during pregnancy can be harmful to the unborn child. Past studies have linked prenatal cannabis use with potential disruption to the child’s cognitive development, low birth weights and pre-term labour; however, recent reports suggest that consuming cannabis during pregnancy may not be as dangerous as we once thought. We’re looking at the current evidence to better understand the true effects (and potential dangers) of using cannabis while pregnant.
Cannabis use during pregnancy
Cannabis is the most commonly used drug in the world and figures show that cannabis use has increased in countries and jurisdictions where the drug has been legalised – whether for medicinal or recreational purposes. For example, a study of pregnant females in California found that the prevalence of prenatal cannabis use increased from 4.2% to 7.1% between 2009 and 2016 (recreational cannabis was legalised in California in 2016).
In some US states where recreational cannabis has been legalised, some dispensaries have even been known to recommend cannabis products to pregnant people for the management of morning sickness and other pregnancy symptoms.
Another study, published earlier this year, aimed to determine whether health service utilisation related to cannabis use during pregnancy in Ontario, Canada increased after the country legalised recreational cannabis in 2018. The researchers found that “the rate of acute care related to cannabis use during pregnancy almost doubled after legalisation.”
In the UK, where medical cannabis was legalised in late 2018, it is highly unlikely that a clinician will prescribe medical cannabis to a patient who is pregnant. While there may be exceptions in serious cases, official guidance recommends refraining from cannabis use during pregnancy and breastfeeding due to the potential risks. Still, pregnant people in the UK and all around the world are continuing to use cannabis – but why?
Are there any benefits?
There is no doubt that a significant number of pregnant people continue to use – or even begin using – cannabis during pregnancy. However, given the stigma that still surrounds cannabis use, particularly during pregnancy, understanding why may not be so straightforward. Luckily, anecdotal reports and a (slowly) growing body of research may provide some answers.
For example, a 2021 study titled “Reasons for cannabis use during pregnancy and lactation” interviewed 52 individuals from across Canada who had decided to continue, cease or decrease their cannabis use during pregnancy and while breastfeeding. The researchers identified three categories of reasons that people use cannabis before and during this time: “sensation-seeking for fun and enjoyment; symptom management; and coping with the unpleasant but nonpathologised, experiences of life.”
While participants endorsed the three reasons for using cannabis fairly equally before pregnancy, there was a clear shift to using cannabis primarily for symptom management during pregnancy. In fact, all but one of the 30 participants who continued to use cannabis during pregnancy reported doing so for symptom management – most commonly, to manage pregnancy-related nausea and vomiting.
While more clinical research is needed to fully understand, and therefore support, the drug’s anti-emetic potential, medical cannabis may be used for the management of nausea and vomiting in other settings. For example, in the UK, chemotherapy-induced nausea and vomiting is one of only three indications for which the National Institute of Health and Care Excellence (NICE) recommends that medical cannabis be considered. It should also be noted that some pregnant people may continue to use cannabis to self-medicate for other existing conditions, such as anxiety.
Of the 22 participants of this study that stopped cannabis use during their pregnancy, the majority quoted potential harm to the developing foetus as their reason for cessation.
What are the perceived risks of using cannabis during pregnancy?
In many cases, pregnant people may feel that the potential benefits of using cannabis during pregnancy outweigh the potential risks, particularly considering that these risks are still not fully understood – or even proven. So, what are these potential risks?
Past studies have suggested that cannabis use may be associated with a number of adverse neonatal outcomes. For example, a 2020 study concluded that infants of mothers who still used cannabis at 15 weeks into the pregnancy had lower mean values in birthweight and gestational age at birth, compared with those born to mothers who had never used cannabis. The researchers, therefore, concluded that “continuing to use cannabis during pregnancy is an independent risk factor for poorer neonatal outcomes.”
Other reports indicate that cannabis use during pregnancy may impair the cognitive development of the unborn child. A 2011 review concluded that prenatally cannabis-exposed children display cognitive deficits and suggested that maternal cannabis consumption can interfere with the “proper maturation of the brain”.
But the results of another recent study suggest that this may not necessarily be the case. The review analysed the results from studies that examined the cognitive performance of offspring exposed to cannabis in utero. According to the authors of the review, the current evidence doesn’t suggest that cannabis exposure alone is associated with clinically significant cognitive functioning impairment.
Using cannabis while breastfeeding
But health experts don’t recommend refraining from cannabis use only during pregnancy, but also while breastfeeding. The active components of cannabis, including THC, can be excreted into breastmilk and so be passed on to breastfed infants. The effects of such exposure are also not fully understood. While one study suggested that cannabis use may alter the composition of human breastmilk, other studies found that “occasional cannabis use during breastfeeding did not have any discernible effects on breastfed infants.”
It is clear that much more high-quality research is needed before we are able to draw clear conclusions on the true effects of cannabis use during pregnancy and breastfeeding. What is clear, though, is that stigmatising people who do choose to use cannabis at these times can be harmful to both them and their unborn children.
